Few minutes ago I downloaded Silverlight 3 documentation as CHM file so I can read it while I am offline. After I unzipped the file, I launched it to view silverlight documentation. I could not view the help content. Instead I got the following error message in the details view.

Navigation to web page was cancelled

I knew what this error was because lot of my HTML Parser clients have run into this issue and I have given them the solution. But I never took time to post the solution on the site to settle it once and for all. This actually is not an error or there is nothing wrong with the file itself. You see this behavior because of one of security patches introduced in Windows XP. Because of a security hole, hackers were able to exploit CHM files to introduce malicious piece of code into user's machines. So now when you download a CHM file from internet, the operation system knows that it came from internet zone so it blocks opening of this file. Here are the steps you will need to follow to view any CHM file that you download from internet.

1. Right click on the file and bring up properties of the file. You will see the following message at the bottom of General Tab

   

2. Click on Unblock button. You will see that warning message become gray.
3. Click on Apply button and you are done.

You should be able to view the help file now.

Last week I received an email from one of my clients asking for latest help documentation for HTMLParser.Net library. Then I realized it has been couple of years since I updated documentation for that library. I used to use NDoc for generating help files. Since .Net2.0 that project has been abandoned. And then Microsoft introduced Sandcastle project. Initially it was buggy to the extent that it used to crash all the time when I generated documentation for my library. So I kind of abandoned it. Last night I went back to Sandcastle site and was glad that the project is still alive is being updated regularly. So I decided to give it a try. Well it still has some bugs and still crashed on my library. But this time I was able to follow the error stack trace and figure out what area may be giving it trouble. It turned out that my XML comments had some text that was colliding with some XML reserved keywords. After removed that, it worked like a charm. So if you are thinking of generating help file for your .Net class library, here are some simple steps that you can follow:

• Install Sandcastle. This is framework for generating help files.
• Install Sandcastle Help File Builder. This is GUI application that is very much like NDoc.
• Compile you .Net class library project with XML documentation option turned on.
• Launch Help File Builder application and add your assembly file and related XML file to documentation resources node.
• Build help file

If you have any questions about usage feel free to drop me a line.